Summary: Major cleanup of the G1CollectorPolicy class. It removes a lot of unused fields and methods and also consolidates replicated information (mainly various ways of counting the number of CSet regions) into one copy.
Reviewed-by: johnc, brutisso

Reviewed-by: johnc, brutisso, poonam

Summary: Keep track of all the old regions in the heap with a heap region set.
Reviewed-by: brutisso, johnc

Summary: _cset_rs_update_cl[] was indexed with values beyond what it is set up to handle.
Reviewed-by: ysr, jmasa, johnc

7102191: G1: assert(_min_desired_young_length <= initial_region_num) failed: Initial young gen size too small
Summary: initial_region_num actually not needed.
Reviewed-by: tonyp, johnc

7102445: G1: Unnecessary Resource allocations during RSet scanning
Summary: Add a new per-worker thread line in the PrintGCDetails output. GC Worker Other is the difference between the elapsed time for the parallel phase of the evacuation pause and the sum of the times of the sub-phases (external root scanning, mark stack scanning, RSet updating, RSet scanning, object copying, and termination) for that worker. During RSet scanning, stack allocate DirtyCardToOopClosure objects; allocating these in a resource area was causing abnormally high GC Worker Other times while the worker thread freed ResourceArea chunks.
Reviewed-by: tonyp, jwilhelm, brutisso

Summary: Acquire the pending list lock in the prologue method of G1's concurrent VM_Operation and release the lock in the epilogue() method. The locking/unlocking order of the pending list lock and the Heap_lock should match that in the prologue and epilogue methods of VM_GC_Operation.
Reviewed-by: tonyp, ysr

7097516: G1: assert(0<= from_card && from_card<HeapRegion::CardsPerRegion) failed: Must be in range.
Summary: Introduced a version of is_in_reserved() that looks at _orig_end as opposed to _end.
Reviewed-by: tonyp, stefank

Summary: Add a new, separate, pointer to the base of the array of discovered reference lists and use this new pointer in places where we iterate over the entire array.
Reviewed-by: ysr, brutisso

Summary: Removed unused fields and methods, removed the G1CollectoryPolicy_BestRegionsFirst class and folded its functionality into the G1CollectorPolicy class.
Reviewed-by: ysr, brutisso, jcoomes

Reviewed-by: ysr, brutisso

Summary: Removed the code for skipping over NULL regions in _markedRegions, replacing it with an assertion that a NULL region is never encountered; removed dead methods, remove() and remove_region(), and inlined a simplified addRegion() directly into fillCache().
Reviewed-by: brutisso, tonyp

Summary: Declare GrainBytes, GrainWords, and CardsPerRegion as size_t.
Reviewed-by: jcoomes, tonyp, jmasa

Summary: Remove the extra guard to allow G1 to use ReduceInitialCardMarks
Reviewed-by: jmasa, tonyp, johnc, ysr

Reviewed-by: kvn, twisti, jrose
Contributed-by: NKurt Miller &lt;kurt@intricatesoftware.com&gt;, Greg Lewis &lt;glewis@eyesbeyond.com&gt;, Jung-uk Kim &lt;jkim@freebsd.org&gt;, Christos Zoulas &lt;christos@zoulas.com&gt;, Landon Fuller &lt;landonf@plausible.coop&gt;, The FreeBSD Foundation &lt;board@freebsdfoundation.org&gt;, Michael Franz &lt;mvfranz@gmail.com&gt;, Roger Hoover &lt;rhoover@apple.com&gt;, Alexander Strange <astrange@apple.com>

Summary: When refactoring the code for a previous fix, a condition was not correctly negated which prevents the G1 policy from adding the correct number of old regions to the CSet when the young gen size is fixed. The changeset also fixes a small syntactical issue in g1ErgoVerbose.hpp which is causing compiler warnings.
Reviewed-by: brutisso, ysr

Reviewed-by: brutisso, johnc

7097053: G1: assert(da ? referent->is_oop() : referent->is_oop_or_null()) failed: referenceProcessor.cpp:1054
Summary: During remembered set scanning, the reference processor could discover a reference object whose referent was in the process of being copied and so may not be completely initialized. Do not perform reference discovery during remembered set scanning.
Reviewed-by: tonyp, ysr

7086533: G1: assert(!_g1->is_obj_dead(obj)): We should not be preserving dead objs: g1CollectedHeap.cpp:3835
Summary: Some objects may not be marked in the event of an evacuation failure in a partially young GC, during a marking cycle. Avoid this situation by not allowing partially young GCs during a marking cycle.
Reviewed-by: tonyp, ysr, brutisso

Summary: Fixed a few inconsistencies in the monitoring data, in particular when reported from jstat.
Reviewed-by: jmasa, brutisso, johnc

Summary: G1 now uses two reference processors - one is used by concurrent marking and the other is used by STW GCs (both full and incremental evacuation pauses). In an evacuation pause, the reference processor is embedded into the closures used to scan objects. Doing so causes causes reference objects to be 'discovered' by the reference processor. At the end of the evacuation pause, these discovered reference objects are processed - preserving (and copying) referent objects (and their reachable graphs) as appropriate.
Reviewed-by: ysr, jwilhelm, brutisso, stefank, tonyp

Reviewed-by: jcoomes, johnc

Summary: Cast HeapRegion::GrainBytes to size_t in output statement.
Reviewed-by: ysr, brutisso, pbk, tonyp

Summary: The desired min / max heap sizes are miscalculated at initialization when NewRatio is used. The changeset also includes an additional small change to turn a print statement into a warning.
Reviewed-by: johnc, jmasa, ysr, brutisso

Summary: Displays the elapsed time taken to perform reference processing during remark as part of the PrintGCDetails output.
Reviewed-by: ysr

Summary: As a result of the changes for 7080389, an evacuation failure during an initial mark pause may result in some root objects not being marked. Pass whether the caller is a root scanning closure into the evacuation failure handling code so that the thread that successfully forwards an object to itself also marks the object.
Reviewed-by: ysr, brutisso, tonyp

Summary: Extend the SA to recognize the G1CollectedHeap and implement any code that's needed by our serviceability tools (jmap, jinfo, jstack, etc.) that depend on the SA.
Reviewed-by: never, poonam, johnc

Reviewed-by: brutisso, ysr

Summary: Make G1 handle young gen size command line flags more consistently
Reviewed-by: tonyp, jwilhelm

Summary: Fixed inconsistencies and mistakes in the young list target length calculations so that a) the calculated target length is optimal (before, it was not), b) other parameters like max survivor size and max gc locker eden expansion are always consistent with the calculated target length (before, they were not always), and c) the resulting target length was always bound by desired min and max values (before, it was not).
Reviewed-by: brutisso, johnc

Summary: It introduces ergonomic decision logging in G1 for the following heuristics: heap sizing, collection set construction, concurrent cycle initiation, and partially-young GC start/end. The code has a bit of refactoring in a few places to make the decision logging possible. It also replaces alternative ad-hoc logging that we have under different parameters and switches (G1_DEBUG, G1PolicyVerbose).
Reviewed-by: johnc, ysr

Summary: Remove the sentinelRef and let the last Reference in a discovered chain point back to itself.
Reviewed-by: ysr, jmasa

Summary: Remove the macro assembler routine br_on_reg_cond() and replace the remaining calls to that routine with an equivalent.
Reviewed-by: kvn, iveresov

Summary: Refactor code marking code in the evacuation pause copy closures so that an evacuated object is only marked by the thread that successfully copies it.
Reviewed-by: stefank, brutisso, tonyp

Summary: Call {pre,post}_full_gc_dump() before and after a STW full gc of G1CollectedHeap. Also adjusted the prefix message, including the addition of missing whitespace.
Reviewed-by: brutisso, tonyp

7081064: G1: remove develop params G1FixedSurvivorSpaceSize, G1FixedTenuringThreshold, and G1FixedEdenSize
Summary: Remove three develop parameters we don't use.
Reviewed-by: brutisso, jwilhelm

Summary: Removed the possibility to turn off generational mode for G1.
Reviewed-by: johnc, ysr, tonyp

Summary: Refactor the allocation code during GC to use the G1AllocRegion abstraction. Use separate subclasses of G1AllocRegion for survivor and old regions. Avoid BOT updates and dirty survivor cards incrementally for the former.
Reviewed-by: brutisso, johnc, ysr

Summary: Align the reserved size of the heap and perm to the heap region size to get a preferred heap base that is aligned to the region size, and call the correct heap reservation constructor. Also add a check in the heap reservation code that the reserved space starts at the requested address (if any).
Reviewed-by: kvn, ysr

Summary: In root processing, move the scanning of the reference processor's discovered lists to before RSet updating and scanning. When scanning the reference processor's discovered lists, use a buffering closure so that the time spent copying any reference object is correctly attributed. Also removed a couple of unused and irrelevant timers.
Reviewed-by: ysr, jmasa